In order to improve sensitivity of a silver halide photographic emulsion and to improve sharpness, graininess and sensitization efficiency using a sensitizer as well as to improve covering power etc., it is known that so called tabular silver halide grains having a grain diameter considerably greater than grain thickness are preferred. Process for producing tabular grains and technology using the same are disclosed in U.S. Pat. Nos. 4,386,146, 4,504,570, 4,478,929, 4,414,304, 4,411,986, 4,400,463, 4,414,306, 4,439,520, 4,433,048, 4,434,226, 4,413,053, 4,459,353, 4,490,458 and 4,399,215.
Also, a recent trend for processing of silver halide light-sensitive materials is directed toward rapid processing.
In general, where the silver chloride content of the grains increases, water solubility increases so that development and fixing are achieved in a shorter period of time and silver halide suited for rapid processing is obtained.
However, silver halide grains having a high silver chloride content generally tend to take the form of cubic grains, and in order to render them tabular grains, certain steps must be taken. With respect to high silver chloride tabular grains having a silver chloride content of 50 mol% or more, a method in which grains are formed without incorporating bromide ions and iodide ions inside, maintaining pAg and pH in ranges of 6.5 to 10 and 8 to 10, respectively and using ammonia is described in U.S. Pat. No. 4,399,215, and a method in which grains are formed in the copresence of aminoazaindene and a peptizer containing a thioether bond is described in U.S. Pat. No. 4,400,463.
In U.S. Pat. No. 4,414,306, there is disclosed a method which comprises simultaneously introducing silver ions, chloride ions and bromide ions and maintaining a molar ratio of the chloride ions to the bromide ions in a reactor in a range of 1.6:1 to 256:1 and a concentration of the total halogen ions in the reactor in a range of 0.10 to 0.90 normality, to allow a silver halide layer having a mean molar ratio of the chloride ions to the bromide ions up to 2:3 to grow in annular tabular grain regions.
Tabular grains containing these chloride ions have an advantage in that processing time for development, fixing, etc. is shortened. However, these type of tabular grains suffer from serious drawbacks inherent to tabular grains in handling, such as fog caused by pressure, desensitization due to pressure, etc. and have properties that are not always preferable from a practical point of view.
In addition, tabular grains tend to become aggregated because the ratio of surface area to volume is large as compared to spherical grains. This often causes problems upon preparation of photographic emulsions or upon coating of these emulsions. This problem is considered to be inherently due to the shape itself of conventional tabular grains.